Scientific Forecaster Discussion
000 FXUS61 KPBZ 211822 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 222 PM EDT Mon Oct 21 2019 .SYNOPSIS... Strong cold front will bring rain and gusty wind overnight into Tuesday. Breezy conditions will continue under high pressure on Wednesday, with near seasonal temperature and dry conditions expected through Thursday. && .NEAR TERM /THROUGH TONIGHT/... Showers associated with the warm front continue to track north and east across western OH. While some of the convective allowing models suggest this will make it into our westernmost zones, the current track of precipitation, low-level jet axis, and prevalence of dry air should limit measurable precipitation. Thus, PoPs were kept low/negligible. The bulk of the rain will arrive with the cold frontal passage, which is progged to approach eastern OH tonight and western PA early Tues morning. Timing with the latest run of models has changed little, so the only minor adjustments were made during this time frame. Strong forcing and climatologically high PWAT values will support an efficient period for rainfall which reinforces the categorical PoPs. Strong warm advection/southerly flow will keep temperatures elevated overnight, with lows 10-15 degrees above seasonal norms. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... Surface cold front will complete it's passage around midday Tuesday. High pressure will then build over the region through the latter half of the day. Subsidence will support mostly sunny conditions, which should allow for deep mixing/gusty wind as cold advection continues both Tuesday and Wednesday. At this time, momentum transfer values suggest 25-30mph wind gusts will be possible. Surface ridging will remain in place on Thursday, though the trough deepening through the central US will tighten up a baroclinic zone just west of the region. Temperatures will remain near seasonal averages. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... Southwesterly flow ahead of the aforementioned central CONUS trough will return a narrow band of moisture to the region. Shortwave passage through the trough may promote surface low development and precipitation but at this time, the model guidance varies. Generally stayed in line with ensemble guidance and near seasonal temperature through the period. && .AVIATION /17Z MONDAY THROUGH FRIDAY/... High confidence forecast save for onset / end time of precip which could shift +/- 2 hours. VFR weather until a cold front inches closer overnight. Rain should arrive at Zanesville shortly after midnight then take until 10Z until before it reaches Pittsburgh. Once the rain commences, look for a eight hour window of precipitation. For now, given wind speed around 10kts this should keep all airports MVFR at worse for flight categories. FKL and DUJ would not shock me to see a brief drop to IFR CIGS in a heavier shower. The front crosses around 11Z in eastern Ohio and 16Z in the mountains. Rapid improvement to VFR weather can be expected at the tail end of the forecast. Wind will be another concern as sustain speeds will be around 12kts most of the period. Gusts will be in the lower 20kts this afternoon then again late morning Tuesday. Low level wind shear remains a concern between 4Z-9Z. Confidence not high enough to include yet, but given strong low level wind near the surface, something to monitor. .Outlook... Wind gusts over 30kts and sustain speeds above 12kts are possible Tuesday afternoon through much of Wednesday. No other aviation impacts forecast at this time through Saturday. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None.